1. Field of the Invention
This invention relates generally to trench excavation and particularly to trench shields designed to protect workers from cave-ins while working in trenches. More particularly, this invention relates to a coupling for splicing two or more short trench shield spreader tube segments into a longer spreader tube of desired length.
2. Description of Related Art
Digging an open trench to a target depth in different types of soils requires varying degrees of slope angles and berm widths to meet safety standards of the United States Occupational Health and Safety Administration (“OSHA”). Where shoring is used, berms can be abbreviated and workers can enter trenches comparatively safely. Where shoring is not used, however, OSHA guidelines often require a trench shield to protect workers who venture down into the trench to complete its excavation, make adjustments or otherwise work at the bottom of the trench.
Trench shields comprise two vertical panels arrayed on opposite sides of a section of vertical wall trench to hold back a collapsed or sluffed ditch berm. The panels are separated by a plurality of spreaders that hold them in place juxtaposed to the ditch sides. See generally FIGS. 1 and 2. Trench shield spreaders typically comprise tubular steel cylinders of a length adapted to accommodate the trench width. Such tubing typically comes in standard lengths and must be cut to the desired length defined by the trench width, often leaving a fractional piece of tubing which usually is discarded. Made of high-grade steel to enable it to withstand significant longitudinal compressive forces from the trench walls, spreader tubing is quite expensive, and the cost of any trenching project necessarily must include significant wastage from discarded segments of spreader tubing. A need exists for means for using fractional segments of spreader tubing instead of discarding them.